Has anyone crunched the numbers and determined which starship weapon modifier (or combination of modifiers) gives the best dps when comparing [CrtH] (+2% crit chance), [CrtD] (+20% crit damage), and [Dmg] (I think +2% damage, might be more like 2.3%).
I would really like to know before I go shopping.

I don't think anyone has crunched any numbers about those modifiers. I think your best bet would be to use a scrap sheet of paper and compare DPS on weapons with those modifiers from the exchange. I think DPS is a function of damage versus fire rate, so I would think that [Dmg] would mean more than either [CrtH] or [CrtD] since those only modify damage sometimes. I use the Antiproton myself and sometimes my damage is sky high, other times it's not. It all depends on my luck on how many times I score critical hits.

Pure dps would be to use Dmg modifier. Your other two will both get higher dps sometimes but in the long run if you just want pure dps get the Dmg modifier.